Hal’s eye had been caught by what looked like the ruins of an old castle.  Such sights are at least rare in the United States.

“That ruin, do you mean?” asked Mlle. Nadiboff.  “Oh, it is a quaint bit of a castle, only some three hundred years old, though long past in ruins.  I believe it was erected as a stronghold by some wealthy man, in the old days when the pirates from Havana now and then swept along the coast on their raids.  Would you like to see the place, Mr. Hastings?”

“Very much indeed,” Hal admitted, “if you have the time.”

“The time?” Mlle. Nadiboff’s laughter rippled out merrily.  “Why, I have all the time in the world, Mr. Hastings.  I live only to enjoy myself.”

“That must be rather a dull existence, then,” thought Hal, while his pretty companion leaned forward to give the order to the chauffeur, who turned up a road leading to the ruined castle of the old piratical days.

Jack had heard the conversation, and so knew, without asking, for what they were now heading.

As they drew closer they discovered other automobiles near the old castle.

“The place has several visitors to-day?” hinted Hal.

“Oh, yes; it is one of the show spots of this section,” replied Mlle. Nadiboff.  “It does well enough to look about there for a few minutes.  But a ruin like that suggests death and decay, and I—­I love life.”

“Still, that castle is now a part of history,” suggested Hal, “and history, it seems to me, should always be interesting.”

“This stupid young engineer!” fumed Mlle. Nadiboff, to herself.  “He would drive me wild, if I saw much of him.  I think even my slow little captain will prove more romantic.”

Though neither of the submarine boys could yet suspect it, they were soon to stumble into much more than relics of the past.

They were destined to find themselves exposed to one of the greatest surprises of their already eventful lives.

“Here we are,” cried Mlle. Nadiboff, as the auto stopped near the north end of the castle.  “May you discover something to interest you!”

The submarine boys certainly did!

CHAPTER VII

A POINTER “JOLTS” THE SUBMARINE CAPTAIN

There was not much left of the old castle, save the walls, and some badly crumbled ruins of inner buildings.

“The Florida climate doesn’t seem to agree with castles,” suggested Jack.  “I have, an idea that, in Europe, a castle only three hundred years old would last much longer and keep much better.”

“In Europe?” repeated Mlle. Nadiboff.  “Oh, yes; much better.  But then, perhaps in Europe there would be a feeling of veneration for the old that would lead the people to take much better care of their castles.  It would be so in my country, I know.”

“May I ask what is your country, Mademoiselle?” asked Jack, looking up and into her face.